Boilers with top loading on firewood

For many homeowners, heating their home sustainably and effectively is a top priority. Using boilers powered by firewood is a time-tested but efficient way to accomplish this. This article will examine the advantages and operation of boilers that use top loading on firewood, examining the reasons behind their continued popularity as heating options.

There are several benefits to using firewood as the main fuel source for boilers. First of all, firewood can be an affordable substitute for other heating fuels like gas or oil and is frequently easily accessible. Finding their own firewood, whether it comes from nearby suppliers or their own property, gives many homeowners a sense of independence. This independence from outside energy sources and sense of sustainability can both be facilitated by this self-sufficiency.

Simple operation is a noteworthy feature of boilers with top loading on firewood. Because these boilers are made to be simple to operate, users can load firewood from the top instead of needing complicated loading mechanisms. Their dependability and longevity over time are also facilitated by their simplicity, which also increases their accessibility for homeowners.

Another important feature that draws people to firewood boilers is their efficiency. To make sure you get the most out of every load of firewood, modern designs prioritize heat output over fuel consumption. When compared to conventional heating systems, well-maintained firewood boilers can achieve high levels of efficiency, which translates into lower energy costs and a smaller environmental impact.

Furthermore, because of their adaptability in heating different kinds of spaces, boilers with top loading on firewood are frequently preferred. These boilers can be customized to meet a variety of heating requirements, whether you’re looking to heat a single-family home, a cabin, or even larger commercial buildings. They are a good choice for a variety of property sizes and heating needs because of their adaptability.

To sum up, for heating homes and businesses, boilers with top loading on firewood present an alluring combination of simplicity, affordability, efficiency, and adaptability. Homeowners can achieve dependable and environmentally friendly heating solutions that meet both practical and aesthetic requirements by utilizing the power of firewood.

Model Capacity (Liters)
ABC-100 100
XYZ-200 200

Features of solid fuel boilers with the function of upper combustion

The construction of rural homes has become more and more intensive in recent years, resulting in ever-increasing specifications for various kinds of heating equipment. The owners are presented with an option by the autonomous heating system, which operates entirely independently of centralized sources. Solid fuel boilers are becoming a more popular alternative to gas water heating. These heating devices come in affordable and highly technologically advanced models these days. The requirement to regularly refuel heating equipment is the only detail that causes consumers to pause and consider their options before selecting a heating device model.

If not the primary role, then the leading one in the operation of the heating equipment is played by its practicality. Solid fuel boilers need a person to be present at all times, but gas and electric boilers can operate almost entirely on their own. Installing a solid fuel boiler with upper combustion in your home is a practical solution to this predicament. Let’s get to know each other better. What is this kind of heating device and what are its design characteristics?

The main motives that make us pay attention to heating boilers of the upper combustion

Any home appliance can be described by a generalized value called service frequency. This is one of the most important parameters for heating devices. The boiler must operate continuously during the heating season to heat the living spaces and supply hot water for household needs to the occupants. Modern solid fuel boilers are highly effective, strong, and energy-efficient. Firewood, coal, fuel briquettes, and pellets—the fuel used to power the units—are all easily accessible. The only factors influencing the decision are the fuel price and the solid fuel appliance model.

During the winter months, solid fuel units are a true benefit. This pertains to both the substantial financial savings on your own part as well as the effective and high-quality functioning of the self-sufficient heating system. Despite their many benefits, solid fuel boilers have one very important drawback. It comes down to whether or not you should be actively involved in its upkeep.

Cleaning and preparing the unit for use are scheduled tasks that must be completed, albeit not as frequently as you may believe. The regular fuel loading of this equipment is the primary issue that needs to be addressed. The type of heating device and the outside weather determine how often the fuel needs to be loaded. You will need to add fuel to the furnace whether you plan to heat your boiler with wood or coal.

For example, a conventional solid fuel boiler that runs on coal or wood needs two to eight loads a day because it is not technically feasible to automatically feed fuel into the combustion chamber. The number of loads is determined by the boiler capacity, the quality of the fuel resource, and the intensity of heating.

Many homeowners prefer top-loading boilers because they can anticipate more problems with their solid fuel appliances. The occupants of the house will have greater personal freedom with such equipment. You will just need to take pleasure in the coziness and comfort rather than playing the part of a stoker and stoker.

The main feature of heating boilers with the upper combustion method

Manufacturers made the decision to employ both new and traditional technologies in the design of heating equipment in response to the challenges associated with maintaining solid fuel heating devices. The primary goal of the boiler equipment modernization process was to extend the time that a single fuel load would burn. In solid fuel boilers, the upper combustion principle was applied to achieve this outcome.

The upper combustion method of boiler operation is not a radically new technological advancement. The fuel that is put into the furnace burns vertically. Т.е. in a manner distinct from conventional boilers. Starting with the top layer, where a movable distributor provides the required air flow, combustion begins. The air distributor collapses under its own weight as the fuel mass burns through, allowing the next layer to burn. As a result, the loaded fuel burns uniformly layer by layer, producing a significant amount of combustible wood gas.

At this point, the unit’s furnace has reached a temperature of 450 0 C.

The pyrolysis principle is applied at this point. A significant quantity of heat energy is released when the tiny combustion products and the released wood gas are fully burned. Because of the way the unit operates, almost no fuel residue remains in the combustion chamber.

As a point of reference, pyrolysis is an exothermic reaction that releases flammable gaseous matter after organic compounds decompose at high temperatures. Wood gas combustion provides the primary heating for the solid fuel boiler during the combustion process.

Through a metal disk, the wood (pyrolysis) gas enters the second chamber, where hot air is blasted in and ignites it. At this point, the second furnace’s combustion temperature soars to enormous values of 500–800 0 C. Everything is understandable and straightforward. The heating apparatus’s design is the most important factor.

It is also the combustion process that determines the burning rate of the fuel. In heating equipment of the classical type wood is burned quite quickly, giving out the maximum possible heat within a short period of time. In other words, the unit reaches its peak output for a short period of time, after which the boiler starts to lose load without further fuel loading. Constantly loading a new portion of firewood is not always convenient and physically possible. Solid fuel boilers with top loading work quite differently. One load with such an apparatus can be enough for 12, 24 or more hours of operation. The intensity of combustion depends on the load on the heating system.

Everything is understandable and straightforward. The heating apparatus’s design is the most important factor.

Boiler design with top loading

Top-loading heating apparatuses are shaped like candles. This kind of solid fuel boiler has a casing that is shaped like a vertical cylinder. The device’s mechanism of operation dictates the vertical arrangement. Moreover, the device’s double-layered body functions as a heat exchanger. Boiler water circulates from top to bottom between the outer and inner walls, absorbing heat from the combustion of pyrolysis gas.

The loading chamber’s location is determined by the operating principle. Above it is an air heating chamber through which the air distributor travels in an upward and downward direction. The bottom ash pan, located in the lower section of the device, is where the least amount of leftover combustion products enter.

Currently, producers make solid-fuel devices with extended combustion in two different configurations:

  • Units consuming wood and fuel briquettes;
  • devices operating on coal, wood and fuel briquettes.

The majority of the time, boiler manufacturers explicitly state in the technical documentation for the heating boiler how long a single load will last. When working with wood and briquettes, these terms typically range from 24 to 48 hours to 3-5 days when loading the boiler with coal.

For reference: The quality of the fuel has a significant impact on how long the fuel material takes to burn. Hard wood, such as birch, oak, beech, and ash, burns for a very long time and produces a lot of heat. Because pine wood burns more quickly than coniferous wood, the boiler’s working life will be significantly reduced.

Secondary products of wood processing can be utilized in place of firewood, briquettes, and coal for this kind of heater. The availability of the fuel resource must be considered when selecting the kind. You will need to have up to 30–50 kg of ready fuel on hand for a single load. The boiler’s power determines the tab’s height. The range of this parameter in different models is 600-1500mm. There is an even wider range of parameters when it comes to power. Boilers for independent heating with capacities of 8, 10, 20, and 40 kW are currently being produced.

Control system of the heating device with top loading

With the inquiry regarding the boiler’s operating principle and loading technique resolved. Everything is accessible and clear here. Let’s take a look at the control system for this technique below. Controlling the air flow that enters the combustion chamber is the fundamental principle of operation for long-burning boilers. Conventional unit models have a mechanical device that modifies the air masses. Thermostat operation activates the standard flap, which has a chain drive. There is one significant technical drawback to this approach, though.

There is a specific temperature mode selected on the thermostat. The damper changes position to lessen the intensity of combustion when the coolant reaches a specific temperature. Because of the operating unit’s high inertia, a sharp temperature drop is not achievable. The coolant will continue to heat up due to inertia and support the heating system for a while.

The raising of the boiler water heating temperature is linked to the same operating principle. The coolant will rise very slowly in temperature until the boiler reaches its rated output.

When a unit has a fan, the situation is different. When required, the electric device releases air, intensifying the combustion process. The air blower makes it feasible to lessen the heating apparatus’s inertia for prolonged combustion. Automation, which has sensors to pick up even the smallest variations in coolant temperature, is in charge of turning on and off the blower.

The fan can be turned off if it becomes technologically necessary, leaving the smoldering fuel on very little oxygen. Naturally, air will enter the furnace. By using such a scheme, you can lower the coolant’s temperature during slippage, which is a phenomenon brought on by the heating unit’s inertial processes.

As an aside, it will take the heating boiler anywhere from half an hour to an hour to reach its typical operating mode. The expansion tank attached to a single heating circuit is activated in order to turn off the heating. The excess heat from the cooling boiler is compensated for with a tank. A long-burning solid-fuel boiler may take two to five hours to cool completely.

Conclusion. Advantages and disadvantages of this equipment

Once you are familiar with the construction and operation of solid-fuel upper combustion units, you can discuss the benefits of this type of heating equipment with confidence. In more detail, the benefits are primarily as follows:

  • long intervals between the next loadings;
  • high efficiency (80%);
  • convenient and simple way of control;
  • minimum of electronics for the automation system;
  • conventional models are energy-independent devices;
  • high level of technological safety;
  • long service life (10-15 years).

Inertia is the primary drawback of such equipment. Solid fuel boilers are less flexible in terms of operation and technology than gas boilers and solid fuel equipment, which operate on a different principle. Fuel quality has a major impact on how well upper combustion boilers operate. The right humidity level must be present in the firewood used in the furnace. Boiler operation issues can occasionally be traced back to loading capacity.

Long-burning boilers on wood with their own hands, loading 24 hours

A water circuit-equipped solid fuel wood boiler is installed in a home where people live permanently. A classical unit’s fuel deposits happen every 4–8 hours on average. It’s important to keep an eye on the operating boiler. By altering the firing time, one can manually load modern, long-burning wood-fired boilers for 24 hours, which is the best time for the unit to operate without the need for intermediate fuel laying.

Boiler using solid fuel for heating homes and businesses

Solid fuel boilers for heating a private house

The materials used in the construction of the furnace, heat exchanger, chimney, loading and combustion process, and other features distinguish basic models of long-burning boilers with a water circuit on wood for the home.

An apparatus known as a jacket-type heat exchanger or tubular (vertical) register is fitted in a long-burning wood-fired boiler that has a water circuit. In systems with natural circulation, boiling water is virtually eliminated by case design.

The foundation of the solid fuel boiler is the idea of fuel combustion that is both economical and long-term.

A steel long-burning wood boiler has a low thermal inertness when it comes to home heating. Heat-resistant steel used in boiler circuits allows them to withstand abrupt changes in system pressure and temperature. The material’s sensitivity to corrosion, which is exacerbated by the metal’s temperature stress, is a drawback. The steel unit will operate for 15 years between repairs.

Long-term heating and cooling occurs in the walls of the cast-iron heat exchanger of the wood boiler used to heat a private home with radiators. Brittle alloy is not intended to withstand significant modifications to the system’s operating parameters.

Semi-automated boiler using solid fuel

The amorphous nature of cast iron makes it resistant to oxygen corrosion, which is its advantage. If the boiler and cast iron heat exchanger are used properly, their working lives can last up to 25 years.

The long burning unit works on the forced, sequential, directed smoldering of wood from top to bottom, releasing hydrogen, carbon monoxide, and methane. The spread of a flame is slowed down when there is insufficient oxygen. The combustion of flue gas produces additional heat energy. At the boiler outlet, the surface of the heat exchanger is cleaned by the flow of combustion products that escape. One daily loading of firewood is permitted by the design.

Table 1: Cost of solid fuel long-burning boilers

Brand name of boiler (manufacturing nation)

Wood boilers using pyrolysis can run for up to two days on a single fuel load. The product’s price is determined by the manufacturer’s brand, power, and level of automation installed in the device.

Long-burning boilers on wood with their own hands, loading 24 hours

The selection of boiler output is contingent upon the building parameters of the dwelling, such as its area and total heat losses, as well as the local climate zone. A homemade long-burning wood-fired boiler typically has an efficiency of no more than 80%, meaning that the boiler loses one-fifth of the heat generated during fuel combustion.

The generator is prompted to run in the intense combustion mode when there is no heat output. Constant peak loads cause the boiler to wear out too soon and consume too much firewood, surpassing heat loss twice.

The boiler’s solid fuel device

Calculating the size of the firebox for a long-burning wood-fired boiler

The size and equivalent area of the furnace chamber are determined by the type, shape, and length of the firewood. Reference values for specific and volumetric loading density, heat released during the combustion of firewood. The loading volume calculation will aid in determining fuel consumption for the coming season and in setting up locations for fuel storage.

Crucial! The combustion process is impacted by the quality of the firewood. The efficiency of the boiler is decreased by the high tar content of coniferous firewood and the high humidity of freshly cut wood. Raw wood that is not fully burned causes soot and tar to accumulate on the water circuit’s surface as well as the furnace’s and chimney’s walls. Metal oxidizes, conducts heat more poorly, and burns easily.

Table 3. The volumetric heat of combustion for various species of wood

Wood type (humidity not to exceed 20%)

KWh/kg, or calorific value

Firewood specific density, kg/m³

Let’s look at an example of figuring out the wood boiler’s stoking chamber volume. Context:

  • boiler power 10 kW;
  • The volume of one load should ensure the operation of the unit for a day;
  • fuel – birch wood, length of logs 0,60÷0,65 m;
  • wood humidity 20%.

Boiler selection is one way to heat a country home. benefits and drawbacks of using a wood stove to heat water. Features, costs, and descriptions of gas, electric, and solid fuel units.

One kilogramme of birch wood burns to release 4.2 kW of heat energy. 2.4 kg of firewood will be burned per hour at the designated power of 10 kW (10/4.2 = 2.381).

Birch firewood weighs 650 kg per cubic meter. Fuel consumption per hour will be approximately 0,004 m³/h (2,4/650 = 0,0037).

The grate with nozzle must support a weight of approximately 60 kg (2,381×24 = 57,144).

Due to the uneven nature of birch firewood, stoking volume will increase 1.9 times, or up to 0.008 m³/h (0.004×1.9 = 0.0076).

The fuel volume, corresponding to the condition of loading once every 24 hours, is 0.2 m³ (0.008×24 = 0.192).

It is important to give careful thought to the firewood selection for the solid fuel boiler.

With the length of the logs being 0.66÷0.65,65 m, the ideal depth for the firebox will be 0.77 m.

Assume for now that the fuel deposit is 0.6 meters high. 0,5 m is the furnace width (0, 2/0,7/0,6 = 0,476).

The wood boiler’s firebox, which uses birch wood to heat an area of 80 m², measures 0,7 by 0,6 by 0,5 meters when it is in operation. When you consider the thickness of the lining, the size of the heat exchanger, the air and afterburning chamber, the ash pan, and the channels for the removal of flue gas, the finished boiler’s overall dimensions will increase by twice.

The rate at which natural flames spread will be slowed down by controlled and balanced combustion. The homemade boiler will operate for 1.8 times longer if there is a restricted supply of primary and secondary air entering the furnace. This will result in a shortage of oxygen. This allows for a decrease in the estimated firewood consumption and, as a result, the unit’s size.

A solid wood boiler with fuel is a good substitute for gas heating.

Homemade long-burning wood-fired boiler with a vertical furnace (Bubafonya)

By hand, long-burning boilers are mounted from sheet steel with a thickness of 4 x 6 mm, thick-walled pipes with a diameter of 300 mm, and appropriately sized cylindrical containers. The most basic design, known as "Slobozhanka" or "Bubafonya," is put together using a barrel or gas cylinder. The device’s concept is a replication of the "Stropuva" boiler from the Baltic.

The firewood is burned top-down using a vertical firebox capacity. The procedure is followed by the load being uniformly compacted, the wood gases being separated and burned, and the combustion products being released into the chimney.

A vertical pipe supplies primary air to the combustion mirror. The boiler is equipped with a telescopic or static construction installed in its upper wall. The cylindrical furnace’s center is where the piston axis runs. A welded edge creates the space between the collar and the main air supply pipe, allowing the rod to move freely and allowing the least amount of air to enter the air chamber during the afterburning of wood gases.

Illustration of a metal stove featuring a lengthy combustion chamber

Boiler efficiency is increased when pyrolysis gases burn. The air intake is controlled by a flap in the chimney’s upper section. The air flow in the combustion zone is stopped by a disk that has blades that is welded to the bottom. Heat capacity should be taken into consideration while choosing the distributor’s material. The disk’s diameter is marginally less than the firebox’s dimensions.

Dimensions of the "Bubafonya" boiler’s design:

  • the optimum diameter of the housing is 300÷800 mm;
  • boiler height – in the range of 3÷5 diameters;
  • wall thickness 4÷6 mm;
  • disk diameter is less than the cross-section of the furnace chamber by 10%;
  • disk thickness is inversely proportional to the diameter (a heavy pancake will push through the combustion zone and extinguish the flame, a light one will lead to the effect of back burning);
  • Curved blades create a directed turbulent air flow for combustion of pyrolysis gases;

"Bubafonya," a homemade long-burning boiler with a vertical furnace

  • diameter of the air supply pipe is taken as 0.55 of S (cross-sectional area of the chimney outlet);
  • the gap between the pipe and the collar does not exceed 2,5 mm;
  • the height of the air intake pipe (in the lower position) is raised above the collar by 150 mm.

Empirical formulas are used to determine the cross-sectional area of the chimney spigot at the long-burning boiler’s outlet:

S is the outlet pipe’s cross-sectional area (in centimeters or millimeters);

N is the boiler’s heat output (kWh);

1,75 is the empirically determined coefficient (m²h/kW).

Kindly take note! It is not possible to install a tubular heat exchanger within the furnace chamber. calls for an internal design within the chimney or an external cylindrical housing with a larger diameter.

Principle of operation and drawings of pyrolysis boilers with their own hands

Large area houses are heated with the installation of homemade pyrolysis units. The construction of DIY gas generators is made more difficult by the designs of the flue ducts, nozzle, and furnace. Boiler operation is dependent on external factors due to forced circulation of the coolant and air supply to the combustion zone. Reducing the risk of heat energy discharge gate and jacket-type heat exchanger can help lower the chance of emergency boiler breakdowns.

Scheme of homemade gas generator with forced air supply to the combustion zone: 1 – boiler drum; 2 – stoking door; 3 – ash pan door; 4 – a fan of air supply to the combustion zone; 5 – loading chamber and primary fuel combustion zone; 6 – technological hole for cleaning the chimney channels; 7 – combustion chamber of wood gases; 8 – heat exchanger jacket; 9 – flue gas outlet channel; 10 – outlet neck of the chimney; 11 – adjusting chimney spike (11a – handle of the spike); 12 – outlet pipe to the distribution pipeline; 13 – return pipe, through which the cooled coolant comes from the heating system; 14 – sleeve of the control unit (thermomanometer); 15 – hatch for cleaning the chimney channels

The boiler drum is made from 4×5 mm thick sheet steel that is welded together. Firewood loaded in front. Heat radiation heats the air entering the combustion zone and travels to the side walls of the chamber and boiler vault. A rotary bolt on the stoking and ash hatches and a shutter with a deflector guarantee the density and tightness of the furnace chamber. A fan drives air into the furnace chamber.

The furnace and a portion of the pyrolysis gas afterburning chamber are fully covered by the heat exchanger jacket. There is water in the 3÷5 cm hole. The rear wall’s heat exchange is enhanced because the jacket’s other wall is in contact with the chimney channel, and the heat exchanger borders the furnace on one side. The flue gas temperature is lowered to 100oC by the heat exchanger that is integrated into the flue gas flow. The boiler circuit’s internal volume makes up 5·25% of the heating system’s overall capacity.

At the top is the consumer system’s heating medium supply pipe. The return pipe is put in from underneath. Because acid condensate precipitation on the heat exchanger walls erodes steel, it is dangerous to cool the return coolant below 65°C. Installing a bypass valve equalizes the temperature between the supply and return lines in the event that the boiler output is low. An elevator unit and a circulation pump are added to a large house’s boiler circuit.

In the long-burning, handcrafted boilers, the grate supports the fuel load. On the chamotte-covered fire grate rests the glowing firewood. The fuel’s afterburning zone is reached by the combustible gas through the nozzles located in the grate’s body.

The ashtray is filled with ash and ashes. Low-power boilers that evenly distribute the heat load across the mirror, as well as appropriate cast iron standard grates.

Plan for heating a private home using a boiler

The chimney neck is where combustion products leave the boiler and enter the ducts (the above example provides the formula for the chimney neck’s cross-sectional area). If required, the chimney adjustment gate is opened.

In the event of a power outage, the design permits refueling without completely shutting down the boiler or requiring the forced release of thermal energy. Wood gas that glows emerges from the furnace, avoiding the chimney channels and afterburning chamber.

A homemade boiler that runs on natural draft and is energy-independent can be operated thanks to the chimney’s section and height. The six meters of chimney height will provide the pyrolysis boiler’s normal draught.

With their own hands, they create a scale drawing of the long-burning boiler using the data they have collected, which helps them calculate the volume and approximate cost of consumable purchases.

Device schematics for various types of pyrolysis boilers

Crucial! You should consult professionals if you are unable to calculate the boiler parameters on your own. Expert online resources promise to create long combustion pyrolysis boiler drawings by hand. The technical documentation includes video tutorials that include thorough installation explanations.

Installation of wood-fired boilers in the heating system

The ability to manufacture boilers independently requires knowledge and expertise in welding, electrical installation, and locksmithing. It will be helpful to know the basics of physics, heat engineering, material science, and heating system installation regulations.

It is essential to follow safety procedures and guidelines. A well-equipped room and the necessary tools are needed to assemble the boiler.

Ingredients for pyrolysis boiler construction:

  • 6, 5 and 4 mm thick sheet steel (furnace, heat exchanger jacket and body);
  • Angle with 50 mm flange sides (frame stiffeners);

Solid fuel boiler with two circuits and a hot water storage tank

  • steel pipe (strapping of the heat exchanger with the heating system);
  • cast iron grate or round bar with diameter of 20 mm;
  • fireclay brick;
  • centrifugal fan;
  • ready-made doors with reflector, fixing, handle and lock;
  • safety group (temperature sensor, pressure gauge).

Chalk is used to mark welded parts (part number, dimensions, and connection location). At the point of purchase, specialized organizations provide cutting services for the material.

Equipment used to build the boiler:

  • DC welding machine;
  • electrodes (diameter 3÷5 mm);
  • electric drill;

Diagram showing the heating boiler’s connections

  • angle grinders (under the large 230 mm and small 125 mm circle);
  • caliper, tape measure, level.

The boiler’s inner casing is assembled first. Since the structure is in direct contact with the coolant, the strength and density of the welds must be guaranteed.

Installation of wood-fired long-burning boilers with their own hands

The pyrolysis boiler for an independent heating system is housed in a separate, specially designed room that is fire-rated. There is a supply ventilation system installed in the boiler room. The minimum distance between the unit and the walls is 20 cm.

The standard weight for do-it-yourself wood-burning boilers is 250 kg/m². Installation of the unit on a level, stable surface without a foundation is possible if the condition is followed. The installation site extends 15 cm above the unit body’s projection (30 cm ahead of the firebox door).

Buderus Logano’s steel solid fuel boiler design

The floor is covered in cardboard made of basalt or asbestos, with a thickness of 4 x 6 mm. On top is a sheet of 2 mm thick galvanized roofing iron. The boiler legs, which serve as support structures, prevent the body from coming into direct contact with the floor.

Thermal insulation needs to be applied to the chimney’s surface. Sharp temperature swings and chimney condensation can be avoided with insulation. The temperature of the flue gases determines how thick the insulation layer is. Using a sandwich pipe made of stainless steel that can withstand harsh environments is preferable. Install a smoke pump if there isn’t a naturally occurring draft.

Although factory models have better designs in terms of aesthetics, the self-assembled unit satisfies the needs of a specific heating system. Remember that producing ready-made drawings (video) using a long-burning boiler by hand will at least double the cost of arrangement.

In the realm of heating and insulating homes, boilers with top-loading firewood offer a practical and eco-friendly solution. These boilers, designed to be fueled by firewood, provide efficient heating while minimizing environmental impact. Their top-loading feature simplifies the loading process, allowing users to add wood easily without having to open a side door. This design not only enhances convenience but also safety, as it reduces the risk of accidental burns or spills. Boilers with top loading on firewood are particularly suitable for households seeking sustainable heating options, utilizing renewable resources like wood to create warmth efficiently. They represent a smart choice for those looking to reduce their carbon footprint while ensuring effective heating for their homes.

Solid fuel boilers of upper combustion with wood and coal loading

The best option will be long-burning solid fuel boilers when selecting equipment with a big furnace volume, extended autonomous operation, high efficiency, and environmental friendliness. Several factors determine the price, including:

  • Type of fuel: distinguish wood and universal devices (working on coal, briquettes and wood products).
  • Principle of operation: with natural or forced draught.
  • The presence of automation and fans for blowing air, capable of maintaining a given air temperature in large rooms with economical fuel consumption.
  • Power: household appliances are designed for 7 – 40 kW, industrial – up to 95 kW.
  • Body and heat exchanger material: steel and cast iron.
  • Possibility of water heating.

Top burning boilers

Long operation on a single fuel charge is a characteristic of top-burning solid fuel heating devices. As a result, the 2003-certified boiler TM Stropuva ran on its own for 31 hours at a power of 5–6 kW after loading 50 kg of firewood.

Due to what the autonomous operation is realized?

Lack of a class grate and ash pan. A blind tray in the lower section prevents fuel combustion below (upper combustion technology is used to maintain the set temperature).

The furnace has a cylindrical shape. The upper layer of firewood is partially burned by air masses that are fed into the center from above.

The air distributor in the firebox moves: it rises when the firewood is loaded, is supported by fuel during combustion, and then descends when the firewood burns out. As a result, oxygenated air can always reach the top layer of fuel.

Hydrocarbons are partly oxidized in the zone where air masses are supplied. The ash and combustion products ascend to the top of the furnace where they are kept apart from the main combustion zone by a large metal disk.

The known pyrolysis gas is mixed with ambient air behind the disk, where volatile combustion products afterburn and transfer the residual heat to the heat exchanger.

A draught autoregulator is located at the chamber’s inlet, where the volatile fuel components are afterburning. Its purpose is to regulate the flow rate of furnace gas and measure the heat carrier’s temperature based on the body part’s thermal expansion.

The unit functions as a heat exchanger throughout its whole body. Water flows through a system from top to bottom.

The challenge is not in stopping fuel masses from burning, but rather in getting rid of the ash with air streams. Once the boiler is operational, it can be loaded with small amounts of fuel, such as household waste.

How it works?

Two sections make up the combustion chamber. The wood stock stays at the bottom while the firewood burns at the top. Firewood ignites from above rather than below, as is the case with conventional solid fuel devices. The combustion process proceeds to the lower layer of fuel involved in this process as the upper layer burns. This lengthens a single fuel bed’s burning period. There is a 50 kg fuel reserve.

The firebox cylinder’s axis receives air supply from the top via the air distributor, which consists of two plates for wood and a tube for coal and peat. The spreader rotates freely in a vertical direction and is raised to a resting position on a metal beam that is fixed above the fuel that is slowly burning at the furnace’s periphery while stoking wood. Combustible gas is produced by the top layer of firewood, which is situated in the combustion zone.

There is a metal disk above the beam called a "staskoblin." All of the combustible materials in the gases are burned out when the disk is streamlined by the flame and enters the entire combustion chamber, which is a cylindrical space between the air distributor pipe and the furnace chamber wall. A free distributor pipe is located in the center of the cylindrical air heating tank that sits above this chamber. The flue gases exit the unit through the flue pipe on the side after passing through the opening in the wall between it and the inner wall.

A valve in the lower portion of the air chamber opens as the coal burns, adding secondary air to the entire combustion chamber. A bi-thermal draught regulator is located at the top of the unit, at the entrance to the air chamber. It works by determining the temperature mode through the thermal expansion of the unit’s body elements. Users make the adjustments by hand. The room’s air intake occurs either directly or via a box equipped with a ventilation device.

Long burning units have a unique metal device that directs air from above onto the fuel to ensure wood burning is uniform. Air delivery is accomplished through the use of the remote control and the fan. The wood smolders concurrently but does not burn. This is made possible by a shortage of oxygen that is delivered to the combustion chamber through movable nozzles; automation regulates the amount of oxygen supplied. Layer by layer, the fuel in the chamber burns during combustion. The equipment is not designed to have an ash pan or grate, and the tray does not contain any components that facilitate combustion.

Through a cylindrical structure that encircles the entire firebox, door (slotted in the lower part of the unit in height), chimney (above), and cleaning door (below), water heating causes it to circulate from bottom to top. Exceeding the water flow rate specified in the design is not advised as this may cause condensation inside the equipment.

Make sure the cleaning door is tight and close it right away after adding firewood to the coals in order to limit the amount of fuel burned.

Table for contrasting this heating system with others:

Advantages of the systems

The fuel box’s specifications define the burning time for wood and coal, and there are no restrictions. The pyrolysis unit has been modified to demonstrate high efficiency through complete combustion of fuel masses with no residue. This aligns with the operating principle.

The units’ fault tolerance is not determined by intricate automation.

Lithuania has been producing a range of multipurpose devices that run on coal and wood since 2007. A short while later, other manufacturers—including Russian ones—started to produce comparable units.

The units’ design elements, which have a height of almost two meters and occupy a minimal amount of usable space, allow for space savings. For those looking to outfit a small boiler room that cannot accommodate traditional solid fuel equipment, it is a practical choice.

The fuel compartment receives air supply from top to bottom. The air in the upper chamber is heated to its maximum temperature, which causes the air to enter lower and encourages the most complete reaction with the wood. As a result, the maximum efficiency is created, which can range from 10% to 100% of the nominal capacity. This leads to another benefit of the units, which is their superior capacity to heat any size room. The boilers run on the first charge for a few days at a time, depending on the size of the heated building. This removes the requirement for regular fuel loading.

The characteristics of the devices’ shapes allow for their durability. Superior quality, dense, heat-resistant steel is used in their manufacture. The design elements dictate the shaky location of the wood-burning hearth. With the exception of the metal exceeding 400 grams overheating, it moves smoothly from top to bottom. Because they are all detachable, system components with a high failure rate can be altered as needed.

It is acceptable to use an additional device if one boiler is insufficient to heat a sizable space.

The main disadvantages

How should a long-burning solid fuel boiler be selected? Customer testimonials list several drawbacks:

  • Sensitivity to the heat exchanger temperature leads to condensation and corrosion formation at increased circulation rate. Solid fuel cast iron devices are less susceptible to condensate than steel ones.
  • Not always the supercharger copes with the burnt ash. Increasing its volume leads to a drop in the heat output of the heater. Wood boilers with natural circulation require constant intervention with a poker.
  • Fast combustion of the support stick and disk located in the flame to cut off the combustion zone of the fuel in the area of afterburning of volatile elements.
  • Large fractions of fuel, including not split logs, are not recommended for use, which acts as an obstacle to the top burning of firewood. Wet fuel supply is excluded. It is important to ensure maximum drying of firewood.
  • Difficulty of ignition of wood at incomplete loading of the furnace (due to large dimensions).
  • High price.

Varieties of devices

Long-burning solid fuel boilers are categorized by analogy with conventional heating systems, with the exception of their operating principle.

The units’ intended use dictates their power. Stropuva’s range of Lithuanian goods starts at 7KW. Small private homes are the perfect places to install low-power products. Burans from Ukraine can generate 40 kW. When selecting Russian equipment for large spaces, the 95 kW model KT-2E will be the best option. With the 200 kW heat output capacity of the Polish equipment Logika, you can heat an area that is almost 2000 square meters. They are employed to heat offices, workshops, and greenhouses. It’s interesting to note that the Logica brand is also used to produce German Buderus devices. Germans buy them; Poles make them.

Cast iron and steel are used to construct the body and heat exchanger. A long service life is a characteristic of cast iron. This enables the 5-year warranty offered by the designers of the cast iron heat exchangers for Viadrus Lignator heaters. Their limited mechanical strength, wall thickness, and weight—the newest Lignator versions weigh 369 kg—are drawbacks to their use. In contrast, the weight of the steel unit Don KS-T 16 RT at higher power parameters is 160 kg. Steel comes in a range of grades, from the least expensive to the heat-resistant. The fuel box is frequently protected with fireclay bricks. It is used for Prometheus heating appliances made by Sibenergo, a Novosibirsk factory.

Solid fuel boilers have the capacity to supply the building with an additional hot water supply. This necessitates the use of a storage tank or a flow heat exchanger to heat the water. Units with water circuits in the first scenario have to fulfill the requirements of increased heat output and efficiency.

When the minimum operating mode is selected, a wood boiler can burn fuel for up to 31.5 hours or longer. Coal-processing devices are distinguished by a burning time of one to three days. Efficiency can attain 85%.

Catalog with prices

Particularly in places where firewood is easily accessible, boilers with top loading on firewood provide a useful and effective way to heat homes. These boilers are made to be as convenient as possible while requiring the least amount of work possible to keep up a consistent supply of heat during the winter.

The simplicity of use of top-loading boilers is one of their main benefits. Refueling is made easier by loading firewood from the top, which does away with the need to reach the firebox from the front or side. This stove’s design improves safety and lowers the possibility of burns or other mishaps that are frequently connected to front-loading stoves.

The longer burn times that these boilers provide are an additional advantage. Loading firewood from the top allows you to fit more wood inside at once and extend the time between refills. They are therefore especially appropriate for homes looking for a heating solution that needs less maintenance.

Moreover, top-loading boilers on firewood are frequently commended for their effectiveness. A sealed chamber that optimizes the combustion process ensures efficient heat extraction and distribution throughout the house. In the long term, these boilers are a cost-effective option because they optimize heating output while minimizing fuel consumption.

To sum up, for homeowners looking for dependable and effective heating solutions, boilers with top loading on firewood offer a compelling alternative. They’re a wise investment because of their high efficiency, long burn times, and user-friendly design, especially for people who live in areas with easy access to firewood. These boilers can offer a sustainable and green means of ensuring that homes are warm and cozy throughout the winter with the right upkeep and care.

Video on the topic


Mine boiler.Kholmova boiler.Top loading.Main pros and cons.

What type of heating you would like to have in your home?
Share to friends
Sergey Ivanov

I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

Rate author
Add a comment